The invention relates to such treatment of cellulose fiber material, e.g. chips, suspended fibers, sawdust and similar, which takes place in the cellulose industry with e.g. impregnated, prehydrolized or cooked fiber material before or after defibration, unbleached or bleached fiber suspensions etc., mainly consisting in that the fiber material during a stage of the manufacture through steaming, impregnation, cooking or other treatment reaches a specific weight higher than that of a liquid in which the fiber material is suspended and even higher than a treatment liquid, and by its sinking movement by its own weight, e.g. through a container, is met by an upward flowing treatment liquid and that liquid is separated and discharged from the upper end of the container.
For the method according to the invention the essential characterization consists in the omission of screens or strainers during the separation of fiber material and liquid. Thus, the fiber material is fed continuously through an inverted into the upper part of a treatment container filled with a suspension liquid and after piling up to a level just underneath the invested funnel opening and after a certain retention time in the container, the treated fiber material is continuously discharged from the container lower end. Above the fiber material surface there is a certain liquid volume. Furthermore, treatment liquid is added close to the bottom of the container and this liquid is flowing upwards counter-currently to the fiber material flow in order to displace the suspension liquid. Upflowing liquid is separated from the surface of the fiber material into the liquid volume around the inverted funnel. By choosing proper funnel dimensions the upflow liquid velocity around the funnel can be kept relatively low so that even light fiber material particles will not tend to be carried or floated upwards. Also the liquid outlets from said volume should be located at a relatively high level compared to the inverted funnel outlet in order to stabilize the liquid flow. Thus, fiber material particles will get time to sediment or settle on the surface of the other fiber material and thereafter follow it downwards.
The commonly known problem within the cellulose industry with plugged strainers in connection with separation of fiber material and liquid can therefore by means of such treatment of the fiber material be considered solved. The invention is even directed at an apparatus suitable for the working of the method.